Technical Field
The present disclosure relates generally to an anvil assembly which is suitable for use with a circular anastomosis stapler. More specifically, the present disclosure relates to an anvil assembly having a tiltable head which is suitable for use with a circular anastomosis stapler.
Description of Related Art
Circular anastomosis staplers which include an anvil assembly having a tiltable anvil head are known in the art. Such tiltable anvil heads have been disclosed in U.S. Pat. No. 7,431,191 (“the '191 patent”) and U.S. Publication No. 2008/0230581 to Marczyk (“the '581 Publication”), the contents of which are incorporated herein by reference in their entirety. In some known circular anastomosis staplers, a locking collar or a backup plate located within the anvil assembly is positioned to inhibit tilting of the anvil head of the anvil assembly prior to firing of the stapler. Upon firing of the stapler, a knife blade of the stapler engages or becomes embedded into the locking collar, and moves the locking collar to a position which allows the anvil head to tilt upon retraction of the knife blade from the locking collar. If the locking collar sticks to the knife blade upon retraction of the knife blade, the locking collar may return to its position preventing tilting of the anvil head. Thus, the anvil head will not tilt.
In order to effect tilting of the anvil head upon retraction of the knife blade, both the '191 patent and the '581 Publication disclose a plunger and a plunger spring which engage a post on the anvil head to tilt the anvil head. To inhibit the locking collar from sticking to the knife blade and, the '191 patent and the '581 Publication disclose a retainer clip and a pivotal latch assembly, respectively, to engage the locking collar upon retraction of the knife blade.
Despite recent improvements to circular anastomosis instruments, a need still exists for an anvil head assembly with a simplified mechanism to effect tilting of the anvil head and to inhibit the locking collar from sticking to the knife blade upon retraction of the knife blade.